The present invention relates to plunger sealing and lubricating apparatus for horizontal plunger pumps for use in power sprayers or the like, and more particularly to plunger sealing and lubricating apparatus of the type having a liquid passage extending from a void space between the front and back sealing packings to the suction chamber.
The plunger pump is usually required to have sealing packings replaced when liquid leaks substantially out of the pump body. Otherwise the leaking liquid will stain the casing of the pump. If the liquid is odorous or toxic, additional problems are created.
An apparatus for plunger pumps is in the prior art that comprises front and back sealing packings, a grease packing disposed therebetween, and a liquid passage extending from a space between the front and grease packings to the suction chamber, whereby liquid leaking from the front packing returns to the suction chamber through the passage.
The apparatus as described above has disadvantages in that the grease is dispersed to enter the suction chamber together with liquid. Another disadvantage is that the back sealing packing as a final barrier has the backward portion insufficiently lubricated with the result that it wears and leaks develop soon through use.
Pursuant to the present invention, there is provided a plunger sealing and lubricating apparatus for horizontal plunger pumps, which comprises a packing room provided for each plunger in the rear portion of the cylinder block. The room including forward and rearward portions and an annular groove therebetween, a packing retainer having the front portion thereof threadedly fitted in the rearward portion of the room and the back portion thereof projecting backwardly from the room, a front sealing packing disposed in the forward portion of the room, a back sealing packing disposed in the back portion of the retainer and having the front side adjacent an inner annular shoulder formed between the front and back portions of the retainer. Further an oiling is positioned behind the back sealing packing in the back portion of the retainer, the oiling packing having a leg drawn down out of the retainer and immersed in oil in an oil-pan secured to the cylinder block, the retainer has a plurality of holes formed in the front portion for internal communication between the annular groove in the room and a space defined by the front and back sealing packings inside the retainer. In addition a passage is provided for internal communication between the annular groove and the suction chamber in the cylinder head, and a conduit disposed in the passage between the cylinder block and the cylinder head. The plunger reciprocates horizontally through the front and back sealing and the oiling packings. The back sealing packing has such a wide frictional surface about the plunger to prevent the leaking of liquid.
For this arrangement, the front sealing packing as well as the front half of the back sealing packing are sufficiently lubricated with liquid coming from the suction chamber and leaking from the front sealing packing. The back half of the back sealing packing is well lubricated with oil provided by the oiling packing behind the back sealing packing. Oil is so separated from liquid as to be prevented from entering the suction chamber together with the liquid. Liquid is prevented from leaking out of the pump body by the wide surface about the plunger of the back sealing packing, thereby returning from the space between the front and back sealing packings to the suction chamber through the passage in the low pressure side. Therefore, the packings can be used for a long time without a leakage problem.
A preferred embodiment of the invention is provided in a pump having a plurality of plungers. The forward portion of the room is smaller in diameter than the rearward portion. The adjacent grooves are connected to each other through the respective channel formed in the cylinder block. An additional inlet port with a removable plug is provided in the upper side of the cylinder and extends from the upper surface of the cylinder block to one of the channels. Thus, if necessary, a secondary liquid line can be introduced through the additional port to the suction side of the pump to which liquid is supplied from the main liquid line.
In one convenient embodiment of the invention, the back sealing packing has a T-shaped cross section to make a wide frictional contact with the plunger. The oiling packing is formed in the shape of a key-hole with the leg drawn outwardly through one of the slits in the under side of the retainer.
In general, it is a fact that the pump of the present invention provides improvements in pumping performance due to liquid lubrication as liquid leaks from the sealing packing. This suggests that the inventive sealing and lubricating apparatus can increase pumping performance.
From the foregoing, it is an object of the present invention to provide an improved plunger sealing and lubricating apparatus for horizontal plunger pumps, in which the packings can be used for a long time without a leakage problem.
It is another object of the invention to provide an improved plunger sealing and lubricating apparatus for horizontal plunger pumps, which can produce improvements in pumping performance.
It is still another object of the invention to provide an improved sealing and lubricating apparatus for horizontal plunger pumps, in which a secondary liquid line can be connected to the main liquid line.
The above and other objects and features of the invention will appear more fully hereinafter from a consideration of the following description taken in connection with the accompanying drawings wherein one example is illustrated by way of example.